1. Field of the Invention
The present invention pertains to the art of refrigerators and, more particularly, to an air flow system for a freezer compartment of a refrigerator.
2. Discussion of the Prior Art
To maintain food storage zones at desired temperatures, a refrigerator will incorporate a system for generating a flow of cooling air which is delivered to various zones of the refrigerator and recycled for further cooling. As is known in the art, such a system includes a closed refrigeration circuit incorporating a compressor, a condenser, an evaporator and an expansion valve. In a typical refrigerator having both freezer and fresh food compartments, the system cycles to provide a supply of cooling air based on the position of one or more manual control knobs and sensed temperatures in the freezer and fresh food compartments. In many known refrigerator arrangements, the flow of cooling air is first delivered to the freezer compartment and then some of the air is diverted to the fresh food compartment. In other known refrigerator arrangements, the flow of cooling air is divided by suitable baffles or the like prior to entering either compartment, with the freezer receiving a higher percentage of the overall air flow.
In any case, the cooling air provided for the freezer compartment must enter the compartment through a suitable inlet, circulate through the compartment and exit the freezer compartment through an air outlet whereby the air can be either returned to the system for further cooling or discharged from the system. FIG. 1 illustrates a typical air flow arrangement for the freezer compartment of a household refrigerator. In this figure, a top mount refrigerator cabinet is generally indicated at 3. Cabinet 3 generally includes a shell 4, an upper freezer compartment 5 and a lower fresh food compartment 7, with the freezer and fresh food compartments 5 and 7 being separated by a mullion 8. Of course, cabinet 3 also includes a lower door 9, having a handle 11 for accessing fresh food compartment 7, and a freezer door (not shown). Freezer compartment 5 is defined by a pair of opposing side walls 15 and 16, a top wall 18, a bottom wall 20 and a rear wall 22, all of which are typically formed as a single liner member that is installed within shell 4 as a unit.
For receiving a flow of cooling air from a refrigeration system (not shown), rear wall 22 is formed, at an upper central portion thereof, with at least one air inlet 26. Air coming in through inlet 26 will flow generally along an upper portion of freezer compartment 5 toward a front portion thereof. The air will then be forced downward toward a set of air outlets or return vents 31 which extend laterally across freezer compartment 5 at the front of bottom wall 20 and lead into mullion 8. Therefore, bottom wall 20 actually defines a false bottom and mullion 8 provides a passageway for the return flow of the cooling air from freezer compartment 5. An example of such a known arrangement is represented in U.S. Pat. No. 3,107,502.
Such an air flow system suffers from various drawbacks. For instance, the vertical dimension of the mullion 8 must be enlarged to provide for the passageway therein while still having enough room for an adequate amount of insulation between freezer and refrigerator compartments 5 and 7. In addition, when multiple food items are stacked atop and in front of other items within freezer compartment 5, these other items may not be adequately cooled through convection as the cooling air will flow well above these items at the rear of freezer compartment 5 and will exit freezer compartment 5 when the flow reaches the lower front portion of freezer compartment 5. Since these conventional systems generally diffuse the air in all directions at the rear of the freezer compartment, they must rely upon the arrangement of the outlet or return vent in the front to get the needed circulation. Furthermore, one or more of the air outlets 31 can be covered by items placed in freezer compartment 5 which could affect the overall cooling system for the refrigerator.
Attempts have been made to improve on such an air flow system by re-positioning the air outlets to a lower rear portion of a freezer compartment. Unfortunately, when the freezer is packed rather heavily, the air must take meandering paths, often through extremely small gaps between the stored items, if it is to return to the outlets. U.S. Pat. Nos. 3,321,933 and 3,365,118 illustrate typical refrigerators of this type.
Based on the above, there exists a need in the art for an improved air flow system for a freezer compartment of a refrigerator. More specifically, there exists a need for a system which will provide for the proper circulation of cooling air within and through the freezer compartment to assure adequate convection cooling of items stored in the a compartment.